Underfloor wiring system



Feb. 3, 1942. J, w LEwlN 2,271,798

.UNDERFLooR WIRING SYSTEM Original Filed Oct. '7, 1937 C/aco/l/ezom r(jITTorQleys Patented Feb. 3, 1942 UNITED STATES PATENT OFFICE UNDERrLoozi SYSTEM Jacob W. Lewin,` Chicago, Ill.

Continuation of application Serial No. 167,681, filed October '7, 1937. This application October 10, 1940, Serial No. 360,612

1 Claim.

The invention relates to improvements in outlet or junction boxes of the type generally employedV in electric wiring installations and more particularly to a box adapted for floor installation.

The present application is a continuation of my copending application, Serial No. 167,681, led October '7, 1937, and is `directed particularly to the combination of a substantially conventional type of flooring with a floor box so constructed and arranged that the conduits leading to and from the box may be arranged to be received within the top oor board whereby the oor 'box can be placed flush with the floor surface, while the conduit cari be extended along the top of the sub-flooring extending within a suitable channel or recess formed in the under-surface of the top floor board.

One object of the invention is to effect improvements in the construction of floor boxes of the above general character whereby a box and its associated wiring fixtures may be installed without materially weakening the floor supporting structure. y

Another object is to provide a novel floor box adapted for quicker and more economical installation.

A further object is to provide a oor box embodying novel means by which the conduits entering the box may be rigidly secured thereto and which provides for effectively sealing the box against the entrance of moisture around the conduits.

With the foregoing and other objects in View,

the invention resides in the construction andnovel combination and arrangement of the parts hereinafter fully described and illustrated in the accompanying drawing, it being understood that various changes in the form, proportions and details of construction may be made by those skilled in the art without departing from the spirit and scope of the invention as expressed in the appended claim.

Referring to the drawing:

Fig. 1 is a perspective View of a floor box embodying the features of the invention, showing the box installed in one type of :door structure.

Fig. 2 is a plan view of the box with the cover removed.

Fig. 3 is a sectional view taken along the line 3--3 of Fig. l, showing the relative positioning of the box and the associated wiring fixtures with respect to the iioor structure. Fig. 4 is a sectional view taken along the same line as Fig. 3, show- T ing a modified form of the floor box.

Fig. 5 is a sectional view taken along the line 5 5 of Fig. 2, showing'details of the conduit clamping means.

Figs. 6, 7 land 8 are sectional views of the floor box utilizing modified forms of conduit clamping means.

The floor box selected to illustrate the invention comprises generally an open topped, rectangular casing 'l of cast iron or other suitable material having openings 8v in each end wall for the reception of conduits 8 through which the electrical conductors enter and leave the box. The rectangular form of the box makes. it particularly suitable for installation infloor structures having a wearing surface consisting of conventional tongued and grooved floor boards I0 supported on a subfloor Il of wood, concrete or other material commonly used for this purpose.

To facilitate installation of thebox, the width of the casing is preferably made to correspond exactly with the width of a oor board Ill. Thus, only one board need be cut to provide a recess for the reception of the box, and since the box presents a square end, the cut may be taken squarely across the board. Further, the casing 'l is of just sufcient depth to accommodate the fittings to be installed therein, thereby enabling it to fit into a relatively shallow cavity or recess in the subfloor Il.

Installation is further facilitated and weakening of the subfloor is avoided by the advantageous positioning ofthe conduit openings 8. In the preferred form of theb'ox illustrated in Figs. 1 to r3, the openings 8 are suitably shaped for the reception of non-circular conduit such as that commonly known as Ovalduct, and are so positioned that the lower edge l2 of the opening will lie in substantially the same plane as the surface of the subiioor H when the box is installed as shown in Fig. 3. With this arrangement of the openings, the Ovalduct may be laid directly on the subfloor and the overlying floor board grooved, as indicated at I3, to provide a suitable channel for the Ovalduct. Thus the groove or slot heretofore required in the subfloor is dispensed With and the attendant weakening of the floor supporting structure is effectually avoided.

The location of the Ovalduct above the surface of the subfloor is also advantageous from the standpoint of installation, as it is a simple matter to form a suitable groove or channel in the floor board to accommodate the Ovalduct. For this purpose, the floor board may be taken up and the grooving performed on a routing or other suitable machine which results in substantial economies in the cost of installation. Moreover, by reason of its small depth, the casing may be received in a relatively shallow recess in the subfloor which can be formed therein with a minimum of labor.

Disposed entirely within the casing I at `each conduit opening 8 is a conduit clamping structure I 4 of novel construction. In the preferred form shown in Figs. 2 and 5 of the drawing, the clamping structure I4 comprises a web I5 extending transversely across the end of the casing and having an enlarged central portion IB in which is formed a longitudinal passage I1 registering with the opening 8 for the reception of the conduit. A shoulder I8 around the inner end of the passage is adapted to engage the end of the conduit and limit the inward movement of the same. A set screw I9 threaded into the web at one side of the passage I 'I serves to clamp the conduit to the casing. The set screw I9 also serves to provide an electrical bond between the casing 1 and the conduit 9.

Novel means is embodied in the conduit clamping structure for providing a water-tight seal around the' conduit. For this purpose, an annular channel 2l) is formed around the inside wall of the passage I'I adjacent the end wall of the casing l, which passage is provided with an upwardly opening vent ZI. When the conduit is in place, a sealing compound may be introduced into the channel through the vent 2 I. .Any suitable compound may be used for this purpose, such as iron cement or certain asphaltic compounds which liquefy when heated and solidify on cooling. The sealing thus provided eiectively prevents entrance of moisture into the box around the conduit and additionally serves to anchor the conduit securely to the box. If iron cement is used, it serves to increase the electrical bond between the casing and conduit.

Any conventional switch, outlet or other fixture may be mounted in the improved box, such fixture being supported on the enlarged portion I8 of the web at each end of the casing. Threaded holes 2Ia for the fixture screwsl are provided i in the portion IB as shown in Fig. 2.

The improved floor box may be modiiied for use with an ordinary cylindrical conduit 9a b-y suitably shaping the conduit openings 8 and clamping structure I 4. As such conduit cannot be accommodated entirely within the groove I3 formed in a -oor board, grooving of the subfloor is necessary. In this case, the conduit opening is positioned so that a substantial portion of the conduit projects above the surface of the subiioor. Ihus the groove in the subiloor may be of minimum depth, as shown in Fig. 4..

The outlet box constructed in accordance with either form above described is provided with a suitable cover 22 arranged to be secured to the box as by screws 23 threading into the web I5 as indicated in Fig. 2. A gasket 2% of cork or the like may be interposed between the upper edge of the casing and the cover to provide yan effective seal against the entrance of moisture. As will be seen by reference to Fig. 1, the various parts of the box are so proportioned so that the upper surface of the cover is flush with the surface of the ioor. The cover, of course, may be formed with a suitable opening for the reception of a plug 25 or other connection of standard construction.

In the modified forms shown in Figs. 6, '7 and 8, the conduit clamping structure comprises a clamping member in the form of a transverse web 26 formed integrally with the casing I and having a suitably shaped, upwardly opening channel 21 in its upper surface for the reception of the conduit. The channel preferably conforms closely to the contour of the conduit to be received in the box, that is, a semi-cylindrical channel is provided for a cylindrical conduit as shown in Fig. 6, and for Ovalduct the channel is formed as shown in Fig. 7. Cooperating with the web 26 is a second clamping member 28 having a corresponding channel 29 adapted to fit conduit therein;

over the upper portion of the conduit to clamp the conduit against the member 26. The member 28 may be secured in place in any suitable manner. As shown in Fig. 6, for example, the screws 23 which hold the cover 22 in place are formed with shoulders adapted to bear against the clamping member. Alternatively, the screws employed for this purpose may be of the ordinary type and carry suitable metal sleeves 30 interposed between the cover and the clamping member as shown in Fig. 7. In a third form shown in Fig. 8, the member 28 is formed at each end with an upwardly bent portion 3| adapted to bear against the underside of the cover plate 22 when the plate is securedto the box.

In the above forms ofclamping structure, the conduit opening may be sealed by interposing a suitablebushing, such as a strip of soft metal, between the conduit and the clamping members. Thus, when the members are clamped together tightly, the metal of the bushing will be forced into the gap between the members as indicated at 32 (Fig. 7) te form a water-tight seal around the conduit, and also will provide Ian electrical bond between the casing and the conduit.

It will be .apparent from the foregoing that the .invention providesa floor boxy of novel form and construction. By reason of the advantageous positioning of the conduit openings, the box and associated fixtures may be installed in a fioor structure without materially weakening the supporting structure. Moreover, the shape and proportions of the casing of the improved floor box greatly facilitates installation. The box further embodies novel conduit clamping structure which permits the conduit to be rigidly secured thereto and provides a water-tight seal effective to exclude moisture from the box. Such clamping structure is located entirely within the casing so that the exterior of the casing is composed of fiat surfaces readily matching the oor structure.

I claim:

In an underoor wiring system for a floor structure, a rectangular metal outlet box having transverse planar end walls, a tubular conduit extending out of one of said end walls adjacent to but spaced below the upper edge thereof, a solid sub-floor, a top oor laid directly on said sub-oor and comprising conventional tongue and groove boards, one of said boards having a longitudinal section omitted of a length equal to that of said box, said :box being of the same width as said board, said sub-floor having a recess therein for receiving the lower portion of said box with said conduit supported on the top of said sub-floor and said box having its surface flush with said top oor and opposite walls in .abutment with the ends of said section, said board having a longitudinally extending recess in the undersurface thereof accommodating said JACOB W. LE'W IN. 

